As disappointing as that is, I'm not really devastated by this. Let me explain why
In the U.S. , the music market is much different than in Japan. Japan, first week sales are the BULK of the total album sales, everything is focused on the first week and then after a few weeks the album drops and drops and drops and usually never reclaims anywhere near the spot it used to be.
In AMERICA, first week album sales are USUALLY the highest, although this is proving to grow weaker and weaker, also first week album sales are NOT the bulk of the album sales. This is how a lot of Japanese artists are able to chart on the United World Chart at number 1, their first week sales are crazy but they plummet there after ( this is why mainting NO.1 on the oricon chart for more than one week is such a huge feat in Japan, it usually signifies a top album of that year)
In the U.S., many artists eventually climb back up the chart and many artists DON'T have the peak sales on the FIRST WEEK. Taylor Swift's album always managed to randomly climb back up to the top 10 sporadically since it has been releasead (usually correlating with her new singles) Christina's STRIPPED album did okay the first week but ended up being one of the highest selling albums released during then. The best example is LADY GAGA who only sold 24,000 her first week (albeit way higher than BoA) and then plummeted off the chart, but as of late she came back to top the chart peaking at No. 4 not too long ago even though she debuted at No. 17 for her first week.
The bulk of sales aren't made during the first week, it's through strong continuous sales in the U.S. that makes albums sell so much. So hopefully BoA will experience this

If she commits to strong promotions like GaGa did by making a lot of performances worldwide and hitting up a lot of small venues to spread her songs to other DJ's, eventually her song could potentially top the Hot 100 which would revitalize her sales. So just because her first week isn't that great, doesn't mean her album has flopped or failed. Maybe in a year if nothing picks up then we can determine that. Hopefully though, with a lot of support, we can spread BoA around and get her up! So everyone start requesting for her songs!

My suggestion though would be to not do as many promotional activities in Asia and focus on the Western World which includes Europe and Australia etc.